1. Field of the Invention
The present invention relates to a communication system and its communication method. More particularly, the present invention relates to a communication system for transmitting and receiving a multimedia packet of a communication terminal, and a media adaptation method of a communication terminal in the communication system.
2. Description of the Related Art
Generally, a communication system provides a communication service for transmitting and receiving a multimedia packet of a communication terminal. One example of such a service is a Multimedia Telephony Service for IP Multimedia Subsystem (IMS) (MTSI). Here, a multimedia packet includes a speech packet and a video packet. That is, in a communication system, a communication terminal can transmit and receive a multimedia packet through at least one radio frequency channel.
At this time, in a communication system, as the number of communication terminals increases or the state of a radio frequency channel is deteriorated, transmission of a multimedia packet between communication terminals can be delayed, or at least part of a multimedia packet can be lost. Hence, a communication terminal regulates a packet unit according to the state of a radio frequency channel, and transmits and receives a multimedia packet according to a corresponding packet unit to reduce loss of multimedia packets. This is referred to as media adaptation.
However, in such a communication system, a communication terminal performs media adaptation based on setting information recorded during the manufacturing process. Hence, it is difficult for the media adaptation to be efficiently performed because the same setting information is used in a communication terminal regardless of its operating environment. That is, it is difficult to restrain loss of multimedia packets of a communication terminal in a communication system.